Power plants – Internal combustion engine with treatment or handling of... – Common receiver having inlets from plural cylinder
Reexamination Certificate
2002-05-21
2003-08-12
Denion, Thomas (Department: 3748)
Power plants
Internal combustion engine with treatment or handling of...
Common receiver having inlets from plural cylinder
C060S320000, C060S322000, C060S321000
Reexamination Certificate
active
06604358
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to an exhaust manifold for mounting on a cylinder head of an internal combustion engine, the exhaust manifold including an exhaust duct disposed within a gas collector housing and in spaced relationship therefrom.
Such an exhaust manifold is disclosed in DE 100 01 287 A1. In this case, a sealing device is arranged between the exhaust-gas collector housing and the cylinder head, the sealing device permitting relative movements between these two components.
EP 0 709 557 A1 shows an exhaust manifold in which each exhaust tube is welded to a flange provided for screwing the exhaust manifold to the cylinder head. Starting from the cylinder head, the exhaust tubes open into a common collector tube which continues to the exhaust pipe.
However, this exhaust manifold is both heavy and expensive and, because of its large mass, removes relatively large amounts of heat from the exhaust gas flow passing therethrough. This reduces the temperature of the exhaust gas, which has the effect of reducing the efficiency of the catalytic converter arranged in the exhaust pipe, particularly during warm-up and in the warm-up phase of the internal combustion engine.
It has already been attempted to counteract this disadvantage, specifically for example, by means of an exhaust manifold according to EP 0 671 551 A1, in which a gas-conducting duct is arranged within a housing. It is disadvantageous here, however, that the weld joint between the outer casing of the exhaust manifold and a flange part connected to the cylinder head has a tendency to leak, and also that the inner tube is directly connected to the cylinder head.
EP 0 765 994 A1 discloses an exhaust manifold for an internal combustion engine with baffle plates welded into its housing, the baffle plates being intended to direct the exhaust gas flowing into the housing towards a discharge duct.
U.S. Pat. No. 4,537,027 describes a further exhaust manifold in which the exhaust gases of all the exhaust-gas bores are passed into a common housing.
However, in the case of the two last-mentioned exhaust manifolds, sealing problems occur due to the lack of gas-conducting duct, which has led to these conceptual solutions not having been adopted for mass production.
EP 0 849 445 A1 discloses a further exhaust manifold. In this case, a sealing device is provided which is of integral design with the exhaust-gas collector housing. However, this does not ensure tightness of the exhaust manifold. Also, the exhaust manifold, which is heated by the exhaust gases, may transfer its heat to the cylinder head and heat the latter in such a manner that damage to the engine may result.
The object of the present invention is to provide an exhaust manifold for mounting on a cylinder head of an internal combustion engine, which exhaust manifold effectively prevents exhaust gases from escaping from the exhaust system, and which is also cost-effective to produce and has a small mass.
SUMMARY OF THE INVENTION
In an exhaust manifold to be mounted on a cylinder head of an internal combustion engine which cylinder head includes a plurality of exhaust passages, the exhaust manifold includes a gas collector housing with a mounting flange, a gas conducting duct arranged within the gas collector housing in spaced relationship and having a mounting collar, and a hold-down element mounted together with the flange onto the cylinder head and including a recess receiving the collar of the gas conducting duct for retaining the gas conducting duct in engagement with the cylinder head but permitting relative movement thereto.
The fact that, according to the invention, the collar of the gas-conducting duct is engaged in the recess of the separate hold-down element permits the gas-collector duct to move so as to accommodate the effect of heat with respect to the sealing device and/or to the exhaust-gas collector housing. To permit such movements advantageously ensures the durability and therefore the operating strength of the exhaust manifold according to the invention and also contributes to isolating noise between the exhaust manifold and the cylinder head.
A shifting of the movements into the plane between the hold-down element and the encircling collar of the gas-conducting duct makes it possible to very readily isolate the gas-conducting duct and the exhaust-gas collector housing from each other in terms of vibration and thermally. Welding can be at least partially eliminated which reduces both the mass and the costs for the exhaust manifold.
The sealing device arranged between the exhaust-gas collector housing and the cylinder head ensures that the exhaust-gas collector housing is sealed with respect to the environment and furthermore permits movements between the exhaust-gas conducting duct and the cylinder head which may be caused, for example, by heat expansion. For this purpose, the recesses on the exhaust-gas collector housing, by way of which the exhaust-gas conducting duct can be connected to the cylinder head via bolts, are also appropriately designed, i.e. for example, as elongated holes.
The gas-conducting duct arranged within the exhaust-gas collector housing forms, together with the exhaust-gas collector housing, an exhaust manifold which is insulated by an air gap and removes, during engine warm-up, a comparatively small amount of heat from the exhaust gas because of the thin walls of the gas-conducting duct and, in particular, because of the air gap between the exhaust-gas collector housing and the gas-conducting duct. This may prevent a reduction in the exhaust-gas temperature and may improve the response and the efficiency of an exhaust-gas catalytic converter arranged downstream. Moreover, the use of the gas-conducting duct described permits a relatively inexpensive material to be used for the exhaust-gas collector housing, since only the gas-conducting duct itself is subjected to a high thermal load. This contributes to a lowering of the production costs for the exhaust manifold according to the invention.
It is particularly advantageous that all of the components of the exhaust manifold according to the invention can be produced by an inexpensive deep-drawing technique which is simple to master and which results in an altogether very inexpensive exhaust manifold. In this connection, the relatively expensive manufacture by internal high-pressure forming can be avoided.
Likewise advantageous is the very small overall size of the exhaust manifold, as a result of which only a very small amount of space is required for installing the exhaust manifold into the engine compartment of a motor vehicle. Furthermore, the exhaust manifold according to the invention has a very small mass, which constitutes a considerable advantage in modern engine construction.
Advantageous embodiments of the invention will become apparent from the description of a preferred embodiment of the invention shown by way of example only, in the accompanying drawings.
REFERENCES:
patent: 4537027 (1985-08-01), Harwood et al.
patent: 5572867 (1996-11-01), Kekkering et al.
patent: 5953912 (1999-09-01), Kaiho et al.
patent: 6082104 (2000-07-01), Hyakutake et al.
patent: 6155046 (2000-12-01), Kato et al.
patent: 6247552 (2001-06-01), Kovar et al.
patent: 100 01 287 (2001-02-01), None
patent: 0 671 551 (1995-09-01), None
patent: 0 709 557 (1996-05-01), None
patent: 0 765 994 (1997-04-01), None
patent: 0 849 445 (1998-06-01), None
Dürr Gerd
Georgs Georg
Härle Hans A.
Tiefenbacher Gerd
Bach Klaus J.
Daimler-Chrysler AG
Denion Thomas
Tran Binh
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